Re: [PATCH] Add hierarchical accounting to cpu accounting controller

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Mon, Oct 27, 2008 at 10:17:03AM +0900, KAMEZAWA Hiroyuki wrote:
> On Sat, 25 Oct 2008 08:38:52 -0700
> "Paul Menage" <menage@google.com> wrote:
> 
> > On Fri, Oct 24, 2008 at 11:01 PM, Bharata B Rao
> > <bharata@linux.vnet.ibm.com> wrote:
> > >
> > > Reported-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
> > > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> > 
> > Reviewed-by: Paul Menage <menage@google.com>

Thanks Paul.

> > 
> > So in technical terms this patch looks fine now. There's still the
> > question of whether it's OK to change the existing API, since it's
> > been in the kernel in its currently (non-hierarchical) form for
> > several releases now.

Hmm... Can we consider this as an API change ? Currently cpuacct.usage
readers of a parent accounting group are missing the usage contributions
from its children groups. I would consider this patch as fixing the
above problem by correctly reflecting the cpu usage for every accounting
group.

> > 
> Hmm..how about having 2 params as "aggregated usage" and "private usage" ?
> 
>  cpuacct.usage.
>  cpuacct.all_subtree_usage.

Is there really a need to differentiate between aggregated and private
usage other than to maintain the current behaviour ?

Regards,
Bharata.